Adapter to mount a filament spool on a thinner axle

thingiverse

This Thing designs an adapter that lets users mount various filament spools on a 3D printer using a narrow axle. Filament spools often have different axle hole sizes, from small to quite large, even if they come from the same manufacturer. If mounted on a 1/2" or 3/4" dowel as an axle, the mismatch between axle diameter and spool opening causes extra resistance, less filament being fed to the hot end, and print quality problems. A year ago, I created a bearing adapter to solve this issue: https://www.thingiverse.com/thing:1203077. Although it works fine, the design is overly complicated, as the bearing is not necessary; the spool will spin freely if all diameters are not too different. To assemble the adapter, you'll need two plates and four spars (STL files for each are provided). The openSCAD source generates one plate and two spars by default, so it needs to be printed twice. A plate goes on either side of a filament spool. Plates are connected by four spars that pass through rectangular openings in each plate. Select openings that most closely match the inside diameter of the filament spool. The original spars were designed for a 1kg filament spool with a thickness of less than 70mm. I've added a STL file for a pair of 33mm spars to fit 250g spools with a thickness of 30mm. The code includes brief comments on how to assemble the adapter, and the pictures document the steps. The last two pictures show the adapter in use on a 1/2" dowel axle. I make no restrictions on this code; feel free to use, modify, share, or distribute it as you see fit.